U.S. drug regulators on Sept. 11 cleared new COVID-19 vaccines to try to counter the poor effectiveness provided by the current options.

The U.S. Food and Drug Administration (FDA) cleared shots from Moderna and Pfizer that will be available to Americans as young as 6 months old later this month.

"Vaccination remains critical to public health and continued protection against serious consequences of COVID-19, including hospitalization and death," Dr. Peter Marks, a top FDA official, said in a statement. "We very much encourage those who are eligible to consider getting vaccinated."

The FDA approved the Moderna and Pfizer vaccines for people aged 12 and older. Regulators granted emergency authorization for the shots for people aged 6 months to 11 years.

There was no mention of Novavax, whose vaccine is also currently available in the United States.

The shots target XBB.1.5, a subvariant of the Omicron virus variant. That subvariant has already largely been displaced by newer strains, including EG.5, according to the U.S. Centers for Disease Control and Prevention (CDC).